Death Shield is a 22nd level cleric Utility power that was introduced in Heroes of Shadow.
Death Shield
Cleric Utility 22
Shimmering tendrils of energy extend from you to your ally, letting you weave a shield that binds her soul to your own.
Close burst 10
Requirement: You must have at least one healing surge remaining.
Target: One ally in the burst
Effect: You lose one healing surge. The first time the target drops to 0 hit points or fewer before the end of your next extended rest the target instead drops to 1 hit point.